Just a quick search of "self-serve drinks Covid-19" and you'll find states that have mandated and businesses (WaWa as a local example) that have, as a result, suspended self serve food and beverages.
A 17 page draft of CDC recommendations for the gradual reopening states -
According to the document, restaurants should move toward disposable menus, plates and utensils; switch to single-use condiments; install sneeze guards at cash registers; and avoid salad bars, buffets and self-serve drink stations.
The document also calls for the use of a cloth mask or face covering by employees when near other employees and customers.
In regards to requiring wearing a mask, it is legal if a State order is issued and the business has proper signage. There's all sorts of stories about the legality of requiring it...just Google it. Here's Maryland -
Gov. Larry Hogan is requiring masks or face coverings to be worn in stores and on public transit beginning Saturday, as Maryland continues to face the coronavirus pandemic.
The order, which Hogan announced Wednesday, comes on the heels of several local governments enacting mask requirements or guidelines, including Baltimore. Cloth masks, homemade masks and bandannas meet the requirements.